Silicate Weathering for Dummies - The Freelance Files MMXCII

chemical weathering of minerals

We've noticed over the years that some people have no qualms about pretending to answer a question using the "spaghetti-test method." That's when you throw a strand of cooked pasta at the wall to see if it will stick. When it came to testing their spaghetti-like writing against the wall of the eHow.com content editor, a lot of pasta was eaten before its time... because the editors were every bit as clueless about the topic as the person who wrote the content. Take, for instance, the Julia Ferrini post at Sciencing.com, "What Is Silicate Weathering?"

We guess that, way back in 2011 when some poor schmuck submitted the question to a favorite search engine, someone had just come across a reference to silicate weathering in response to climate change. There is some evidence that weathering of silicate minerals improves sequestration of atmospheric CO₂, a factoid Ferrini managed to tease out of an abstract that doesn't actually say that. In point of fact, the sometime journalist pounded out q lot of words loaded with factoids, but there was a problem. Julia's text,

• ...differentiates weathering from erosion and mentions physical and chemical weathering...
• (Parrots something she read (without understanding it) that said, "Silicate weathering can help shape the Earth's surface, regulate global and chemical cycles and even determine nutrient supply to ecosystems"
• Explains that, "Silicates make up approximately 95 percent of the Earth's crust and mantle," which is a big "Duh!" since silicates make up 100% of the mantle and its volume is more than 80 times the volume of the crust.
• Prattles about silica tetrahedra, randomly stating that, "The prime makeup for all silicate minerals is the silicon-oxygen tetrahedron..."
• Briefly differentiates between physical and chemical weathering, mistakenly claiming that, "Chemical weathering occurs when the mineral composition of a rock [sic] is altered."
• Misstates the findings of people who actually know what they're talking about, explaining (incorrectly) that "...silicates dissolve inconsistently with weathering as they are attached with [sic] other minerals such as clays."
• Botches her discussion of rock types by telling us that of all silicate rocks, "half [are] metamorphic and 'Precambrian'"

What Julia's text does not do, however, is actually say what constitutes silicate weathering – at least beyond the bogus "the mineral composition of a rock is altered." So let's help her out:

Chemical weathering of silicates, in particular those rich in sodium, calcium, potassium, magnesium, and iron; involves the breakdown of chemical bonds forged at high temperatures in favor of chemistry in an environment rich in liquid water. The resulting minerals (not rocks) are stable at surface conditions and typically include relatively large percentages by volume of water.

Julia could have said that instead of blathering at length about erosion, carbonates, the Precambrian Era, and volcanoes. She didn't... and that's why one of Julia's only two eHow posts has earned her a Dumbass of the Day award.

SI - WEATHERING